The fact that crime novels almost never win major literary prizes is often attributed to cultural snobbery, and that can be a factor. But, as a devotee of detective fiction who has been a judge for many book awards, I have noticed another problem. In the stage of deliberations at which panelists re-read the shortlist, mystery stories are inevitably disadvantaged because a large part of the narrative power – the manipulation of suspense and concealment of identities – has become redundant.

For this reason, the concept of a TV re-run channel for whodunnits seems peculiar. But, six weeks ago, ITV launched Encore, a service available to Sky subscribers (channel 123), which began with a repeat showing of Broadchurch. The channel isn’t limited to detective series – on Wednesday nights, for example, it offers family tiffs, toff families and top lawyers in a triple bill of Life Begins, Downton Abbey and Kingdom – but the early adverts and trailers were led by Broadchurch, and numerous other crime shows also feature in the schedules, including Vera, Whitechapel, Above Suspicion and Scott and Bailey.

Can a whodunnit still work if you know by whom it was done? While there will clearly be new viewers who missed Broadchurch on ITV or DVD, my experience was that, just over a year after the end of the network showing, the developments were too expected. The dialogue and psychology, and the deeply layered performances of Olivia Colman and David Tennant, still give pleasure. But in that so much of the show’s power came from the astonishing implications of the killer’s identity, watching it while already knowing their identity becomes like a game of spot the ball in which the newspaper has accidentally left the X printed on the picture.

The advantage for Encore is that relatively few mystery stories are as widely viewed – or their solutions the subject of such publicity – as was the case with Broadchurch. Revisiting episodes of Vera and Above Suspicion, I was frequently as confused as the first time around.

This is because it is a strange aspect of crime fiction – probably because the eventual revelation of the killer is such a small part of stories that often feature fairly interchangeable crimes and criminals – that the audience often loses the plot soon after completing it. Most fans of the form have had the experience of reading a work by a prolific author and suddenly not being sure if they have read it before.

Even so, seeing a TV detective series through a prism of half-recognition is still a bizarre experience. Watching a whodunnit usually involves pitting your instincts against the tactics of the scriptwriter – if Mrs Plum is behaving guiltily at the end of the first episode, she surely can’t be the killer, unless double bluff is in play – but, on Encore, we watch differently, adding to our intuition the extra element of memory: was this the one where it was the classics teacher? Only with truly ingenious denouements – such as the explanation of the Inspector Morse episode The Silent World of Nicholas Quinn – is a detail likely to have lodged in the viewer’s mind irrevocably.

And, even with plots that are not easily forgotten, Encore has cleverly recognised that, in the crime genre, the climactic revelation need not end the appeal of an attractive franchise. A novelisation of Broadchurch, adapted by the talented crime-writer Erin Kelly from Chris Chibnall’s scripts, is published next month, extending a trend that has included David Hewson turning the Danish series The Killing into books.

It can be supposed that most readers of these volumes will know the ending – Kelly sticks with the Broadchurch killer chosen by Chibnall – but the publishers seem confident that enough people will want to experience the events again, although in a different medium. The cover promises, though, that the novel of Broadchurch contains “never-before-seen” material, which probably means that Kelly has been able to dramatise deleted scenes. So, just as a lover of a novel watches the screen version wondering what has been taken out, a keen viewer of Broadchurch reads the novel wondering what has been put in.

ITV has made clear that the network will eventually screen original dramas, although these would clearly contradict the channel’s name. When Sky Atlantic began to show some British stuff amid the American imports that had been its calling card, a network spin doctor smartly pointed out that the Atlantic has two sides. So perhaps this joint enterprise between ITV and Sky will flag up any new shows as an Encore Premiere and hope that not too many French teachers are among the audience.

Until then, Encore – regardless of the possible economic benefits of the collaboration for ITV and Sky – makes more sense than I thought it might, partly through being a broader church and featuring some non-mystery material, but I still think it’s hard to imagine many viewers watching Broadchurch for a second time so soon.